1. Field of the Invention:
This invention relates to an electronic computer, and more particularly to a small computer such as a portable electronic calculator.
2. Description of the prior art:
Some of conventional small electronic computers, such as portable electronic calculators are capable of performing, besides usual divisions, a calculation to find a quotient Q and a remainder R which satisfy the equation A=D.multidot.Q+R (where Q represents an integer) with respect to a dividend A and a divisor D. Hereinafter, this kind of calculation is referred to as "quotient/remainder calculation". Where the term "division" is used herein, it is understood that the term means a usual division.
An example such conventional electronic calculators which can carry out quotient/remainder calculations is shown in FIG. 5. The calculator of FIG. 5 comprises a display 51, a keyboard 52, and a slide switch 53. The keyboard 52 includes numeric keys 52a for entering a number, a divide key 52b for specifying division or quotient/remainder calculation, an [=] key 52c for execution an arithmetic operation such as a division, and a [REM] key 52d for finding a remainder after execution of a quotient/remainder calculation. The slide switch 53 is a switch for selecting the current operation mode. Operation modes selectable by the slide switch 53 are: REM (remainder) mode for carrying out a quotient/remainder calculation, F mode in which the result of calculation is obtained to the maximum possible number of digits for display, and 3-, 2-, and 0-modes in which the fourth, third, and first decimal places of the calculation result are rounded off respectively so that the calculation result is rounded to the third, second, or zero decimal place. Among these operation modes, REM mode is the only mode in which a quotient/remainder calculation can be carried out.
An example of the operation procedures for division and quotient/remainder calculation in the calculator of FIG. 5, and the calculation result displayed are shown in FIG. 6. In FIG. 6, rows A and B show the operation procedure for division. Initially, the slide switch 53 is operated to select F mode in order to obtain a calculation result to the maximum possible number of digits for display (row A in FIG. 6). When keys are operated as shown in row B in FIG. 6, the required division is carried out. Rows C to E in FIG. 6 show the operation procedure for quotient/remainder calculation. First, the slide switch 53 is operated to select REM mode (row C in FIG. 6). Next, keys are operated as shown in row D of FIG. 6, and a quotient resulting from the quotient/remainder calculation is first computed and displayed as it is. The key operation in row D of FIG. 6 is identical with that in the operation for division in row B, but a different operation result is obtained because the selected operation mode is different. Then, the [REM] key 52d is depressed, then the required remainder is obtained and displayed.
As stated above, with the prior art calculator it is necessary to preselect a particular operation mode (REM mode) for execution of a quotient/remainder calculation when such calculation is to be carried out. This complicates the necessary operation procedure. Another problem is that since the result of the quotient/remainder calculation is displayed in two steps, i.e., first with respect to the quotient and then with respect to the remainder, once the remainder is displayed, the quotient cannot be displayed again. This is very inconvenient in that the calculation result cannot be ascertained time and again.